This invention relates to a device for interfacing the x-ray image intensifier and spot film device of a diagnostic x-ray table. Spot film devices are commonly called "spot filmers" so, for sake of brevity, that term will be used herein.
One type of x-ray table comprises a table body having an x-ray transmissive top on which a patient lies during an x-ray examination. An x-ray tube is mounted inside of the table body on a carriage that is adapted for translating longitudinally of the table top. A column extends upwardly from the carriage at the rear of the x-ray table body for supporting a spot filmer in spaced relationship with the table top. Thus, when the carriage is translated, the spot filmer moves longitudinally in correspondence with movement of the x-ray tube. The stop filmer has a bilaterally movable carriage in it on which a film cassette is supported. The film cassette is shiftable to enable recording several images on different sections of the film in the cassette. There is a collimator associated with the x-ray tube and masks in the spot filmer which defines the boundaries of any film section that is to be exposed. It is necessary to have the center point of each section fall on a line corresponding with the central ray of the x-ray beam that emanates from the focal spot of the x-ray tube to avoid having one or more edges of the image recorded in a section cut off.
X-ray image intensifier assemblies are also frequently mounted on top of the spot filmer to enable making a fluoroscopic exposure of a part of the anatomy of a patient who is on the table top. Prior to making a fluoroscopic exposure, the film cassette is retracted to parked position rearwardly of the spot filmer so as to provide a clear path to the input screen of the x-ray image intensifier. By virtue of having an x-ray image intensifier, three points must now lie on the same straight line, namely, the center point of the image intensifier input screen, the center points of the film sections, and the focal spot of the x-ray tube. Most manufacturers find it problematical to establish the three points along a straight line when the x-ray apparatus is being assembled at the factory and even more difficulty is encountered when the points have to be realigned in the field as is sometimes the case when the image intensifier and spot filmer have been disassembled or separated in the field to enable performance of maintenance procedures on one or the other.